Best Prestige Classes! (archive?)

[TheGrimace]

This space saved for the actual Archive, once I start getting suggestions

[TheGrimace]

Howdy all!
I have fairly recently embarked on an adventure to homebrew a new Dungeons and Dragons system (affectionately dubbed 3.8125). I am keeping the core mechanics that can be found in 3.X, but am attempting to rewrite every detail. What I would love to have from everyone here is a sampling of your favorite prestige classes. I don't necessarily mean the best ones, here is essentially what I look for in a prestige class.

Broad - While a Prestige class can be more specific than a base class, I still want it to be able to span a variety of concepts and be playable in a variety of campaigns. Things like Dragon Slayers drive me nuts because as a DM, they either fight dragons, and this player is way too good, or they don't, and this player is way too weak.

Interesting - The Incantrix, Blood Magus, Arcane Archer all have a very strong concept behind them, and they hold true to that concept. They please me, and other things like this are appreciated.

Balanced - While I will be rewriting the prestige class, ones that are already reasonable balanced make my job a whole heck of a lot easier.

If you're going to say one that you have found on this board (which is great!) please include a link, that would make my archiving job much easier.